The invention involves a device for determining the absolute angular position of a device turning with respect to a fixed structure, a steering system for an automotive vehicle as well as a bearing including such a device.
In numerous applications, especially automobiles such as trajectory control systems or electric power-assisted steering systems, we need to know the absolute angular position of a device turning with respect to a fixed structure.
By absolute angular position is understood the angle separating the position of the turning device at a given instant, from a reference position of a turning device, this reference position is fixed and given with respect to the fixed structure.
By contrast, the relative angular position is the angle separating the device's position from an arbitrary and variable initial position with respect to the fixed structure.
Such a device is known from document EP-1 167 927 which specifically uses an encoder intended to be set in rotation together with the turning device, said encoder includes a main multipolar track and a multipolar track called “top turn” which are concentric, this top turn track includes a singularity so that the associated sensor delivers one pulse per revolution of the encoder. After being placed in service, such a device determines the absolute angular position after the detection of the first top turn pulse.
One limitation of this device is the pulse detection only occurs once per revolution of the encoder. In some cases, it turns out that a significant angular displacement of the turning device should be performed before learning the absolute angular position. And with the known device, it is not possible to increase the number of singularities per revolution of the encoder from the inability to discriminate between them.